bio keystones

biological species concept

a group of organisms that can interbreed and produce fertile offspring

speciation

the process by which new genetically distinct species arise

gradualism

new species arise from the result of slight modifications over many generations

punctuated equilibrium

species are generally stable over long periods of time. occasionally there are rapid changes which can result in a new species

changes in allele frequency

can be caused by natural selection or chance

disruptive selection

selection in which the extremes for a trait are selected for against the intermediate (snail colors)

stabilizing selection

selection against both extremes, intermediate phenotype is selected for instead (medium sized babies)

directional selection

a single phenotype is favored, causing the allele frequency to continuously shift in one direction (javelina and spiky flowers)

genetic drift

a random change in frequency of alleles

population bottleneck

a sharp reduction in the size of a population due to environmental events or human activities; can lead to lack of genetic diversity

founder effect

when a new population is established by a very small number of individuals from a larger population; can result in change in allele frequencies or a lack of genetic diversity

a change in allele frequency by itself

does not lead to speciation

isolating mechanism

some sort of reproductive barrier, or barrier to gene flow is necessary

mechanical or gametic reproductive isolation

some species physically cannot reproduce together or cannot produce viable offspring (hybrid animals, zonkey)

geographical isolation

when two populations are separated by geographic barriers such as rivers, mountains, or bodies of water

behavioral isolation

some organisms develop differences in courtship rituals or other behaviors (fireflies flicker in a patternfor attraction)

temporal isolation

different mating seasons (wood frogs and leopard frogs)

evolution

the connection between selection and genetic change

species

a group of organisms capable of interbreeding and producing fertile offspring

theory

a well-substantiated explanation of some aspect of the natural world, based on a body of knowledge that has been repeatedly confirmed through observation and experiment

biological evolution

a change in the genetic makeup of a population

darwin's ideas

species are not fixed and they can change by some natural process, just like geological structure

artificial selection

human intervention in animal or plant reproduction to ensure that certain desirable traits are represented in successive generations

natural selection

a process where organisms better adapted to their environment tend to survive and produce more offspring, called "survival of the fittest"

compare and contrast artificial and natural selection

both are processes where traits are being chosen. artificial is chosen by humans, while natural is chosen by nature

fitness

an organism's ability to survive and reproduce

survival of the fittest

individuals with characteristics that are not well adapted to their environment will either die or leave few offspring. those that are better adapted to their environment will survive and reproduce most successfully.

adaptation

any heritable characteristics that increases an organisms ability to survive and reproduce

principle of common descent

all species, living and extinct, are descended from ancient common ancestors

divergent evolution

process by which species diverge into two or more descendent species (ex. galapagos finches)

convergent evolution

Process by which unrelated organisms independently evolve similarities when adapting to similar environments (ex. sugar gliders and flying squirrels)

types of evidence

anatomy, embryology, patterns, and molecular data

anatomy components

homologous structures, analogous structures, vestigial structures

homologous structures

same makeup, different functions, evidence of a common ancestor (ex. vertebrate limbs)

homologous structures evolution

divergent evolution

analogous structures

same function, different makeup (ex. bird wings vs insect wings)

analogous structures evolution

convergent evolution

vestigial structures

remnants of structures found in ancestors that no longer function, or not well (whale hip bones)

embryology

similarities in early embryo stages

patterns component

coevolution

coevolution

two species put evolutionary pressure on each other (cows and archaeans)

molecular data

similarities in DNA (hox genes, or other genes)

ploidy

the number of sets of chromosomes in the nucleus of a cell

types of cells

somatic (body cells) and gametes (sex cells)

somatic

body cells that divide genetic material using mitosis

what do body cells create

identical diploid cells

telophase I

nuclear membrane forms around each cluster of chromosomes, and the cleavage furrow forms

gametes

sex cells that divide genetic material using meiosis

what do sex cells create

genetically unique haploid cells

meiosis I

divides homologous chromosomes

meiosis II

divides sister chromatids

how is genetic diversity created?

using crossing over which creates a different combination every time

where does meiosis I occur

in prophase I

pairs of homologous chromosomes form...?

a tetrad and exchange genetic material (crossing over)

prophase I

homologous chromosomes exchange genetic material, and spindle fibers attach to centromeres of homologous chromosomes

metaphase I

homologous chromosomes line up at equator

anaphase I

homologous chromosomes separate (nonidentical sister chromatids remain attached)

why are nonidentical sister chromatids nonidentical?

they are nonidentical due to crossing over

end result of meiosis I

two daughter cells

what follows meiosis I

cytokinesis

why is there no interphase between meiosis I and II?

because it will double the DNA again and restart the process

prophase II

spindle fibers attach to centromere of nonidentical sister chromatids

metaphase II

nonidentical sister chromatids line up at the equator

anaphase II

nonidentical sister chromatids divide

telophase II

nucleus reforms and cleavage furrow forms

end result of meiosis II

four genetically unique haploid daughter cells

why are genetically unique haploid daughter cells genetically unique?

they are genetically unique due to crossing over

haploid

having a single set of unpaired chromosomes

diploid

containing two complete sets of chromosomes, one from each parent

zygote

created when sperm and egg cell combine

nondisjunction

failure of homologous chromosomes or sister chromatids to separate properly during mitosis or meiosis

result of nondisjunction

one daughter cell has both pairs of parental chromosomes or chromatids while the other has none

example of nondisjunction

down syndrome (trisomy 21)

identical twins

same egg and same sperm, the zygote splits a few days after conception

fraternal twins

different egg and different sperm cells for two different zygotes

meiosis

nuclear division in sex cells

polygenic trait

trait controlled by two or more genes

mutations

changes in DNA that affect genetic information

point mutations

changes in one or a few nucleotides

point mutation substitution

one nucleotide is replaced with a different nucleotide

point mutation insertion

one nucleotide is put into the DNA sequence causing a frame shift for all following codons

point mutation deletion

one nucleotide is removed from the DNA sequence causing a frame shift for all following codons

silent mutation

changes a single nucleotide but doesn't change the amino acid created

missense mutation

changes a single nucleotide and changes the amino acid created

nonsense mutation

a premature stop codon

frameshift mutations

shifts the reading frame of the genetic message so that the protein may not be able to perform its function (can be a missense or nonsense)

chromosomal mutation

a change in the chromosome segment structure, it's much more serious than a single gene mutation

chromosome mutation duplication

a copy of the segment is inserted

chromosome mutation inversion

two segments switch places

chromosome mutation translocation

two sections of segments switch places

what does translocation require?

two different chromosomes

neutral examples of mutations

eye color and birth marks

harmful examples of mutation

sickle cell anemia and down syndrome

beneficial examples of mutations

sickle cell anemia's immunity to malaria, and immunity to HIV

what are the two ways DNA can be mutated

by inheritance or if it's acquired

how can DNA be mutated by inheritance?

it can mutated from parent to child

how can DNA be mutated by being acquired?

environmental damage or mistakes when DNA is copied (rare)

ribosome

builds polypeptides, consists of proteins and rRNA, subunits hold tRNA and mRNA close together during translation

genes

subunits of DNA that code for specific protein

1 gene \=

1 protein